Inclination adjusting linkage arrangement for a supporting surface

ABSTRACT

An inclination adjusting linkage arrangement is disclosed for an open care bed or infant warmer having a mattress supported on a mattress base cantilevered from a columnar or vertically disposed &#34;back bone&#34;. The mattress base includes a box like frame over which a sheet is stretched to provide tensioned support for a mattress. Adjustment of the angle of inclination of the mattress base is made possible by the use of a non-parallel arm type system providing a virtual pivot point for the mattress base which may be positioned near the center of the mattress.

This is a divisional of copending application Ser. No. 08/870,223 filed on Jun. 6, 1997 now U.S. Pat. No. 5,980,449.

FIELD OF THE INVENTION

This invention relates to infant care centers and in particular though not solely to infant warmer open care beds for providing an easily accessible open care environment to infants in maternity and new born care facilities and the like.

DESCRIPTION OF THE PRIOR ART

A new born infant requiring medical attention may be placed in either a closed care bed such as an incubator or an open care bed such as an infant warmer. In general an infant warmer has the advantage that a medical care giver has immediate, unlimited and unhindered access to the infant while temperature regulation of the infant is more difficult as the infant is exposed to ambient temperature and air flows.

In most existing infant warmers (warmers) the infant is placed upon a padded or pliable mattress on a support surface beneath a radiant heat source. The infant is partially shielded from draughts by low walls which also serve to restrain the infant from falling from the warmer. Examples of this type of support surface are disclosed in U.S. Pat. Nos. 4,809,677 issued to the BOC Group, 5,162,038 issued to Hill-Rom Company and 5,376,761 issued to Ohmeda Inc.

In each of these prior infant warmers the walls of the mattress support surface are removable although removing the walls entails physically pulling the wall from the support structure and then finding a place to store the removed wall. This procedure can often slow down a care giver and/or aggravate an infant or baby. In addition, the mattress support is bulky and not collapsible so that assembling/disassembling is often not possible or practical for medical personnel and the removal and relocation of the warmer between two locations accordingly involves large, difficult to handle components.

Another drawback due to the solid construction of these prior warmers is that the mattress support surface is itself usually supported by a solid column such that there is no room beneath the mattress support to position medical equipment such as modem portable x-ray machinery. Furthermore, it is often desirable to tilt the mattress forward or backward of horizontal. In prior warmers, this has been accomplished by placing the mattress support surface on a fulcrum or pivot point. The fulcrum or pivot point has necessarily been mounted on a supporting base further reducing the useable area beneath the mattress support.

BRIEF SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide an infant warmer which goes at least some way towards overcoming the above disadvantages or which will at least provide the industry with a useful choice.

For the purposes of clarity, the main statements of invention will be designated A, B, C and D respectively.

A. Accordingly, in a first aspect, the invention consists in a partially enclosed article support structure comprising:

a support surface adapted to receive an article,

at least one article retaining wall means,

axle means provided on said at least one article retaining wall means,

axle receiving means provided on said support structure, wherein said at least one article retaining wall means is rotatably attached to said support surface by the mounting of said axle means within said axle receiving means thereby allowing said at least one article retaining means to be rotated from a raised retaining position to a lowered article access position.

B. In a second aspect, the invention consists in a tensioned article support structure comprising:

rigid frame means having an outer perimeter surrounding an open central portion,

flexible article support surface means having a continuous edge,

beading means attached to said flexible article support surface means around a substantial part of said continuous edge, and wherein said flexible article support surface means is adapted to directly support an article which is supported indirectly by said rigid frame means.

C. In a third aspect the invention consists in an inclination adjusting linkage arrangement for a supporting surface to connect said support surface to a fixed structure means, said linkage arrangement comprising:

first linkage member means having proximal and distal ends, pivotally connected to said fixed structure means at said proximal end at a first position on said fixed structure means,

second linkage member means having proximal and distal ends, pivotally connected to said fixed structure means at said proximal end at a second position on said fixed structure means, there being a first predetermined distance between said first and second positions,

wherein the distal ends of said first and said second linkage members are each pivotally connected to said supporting surface at third and fourth positions respectively, there being a second predetermined distance between said third and fourth positions which is not equal to said first predetermined distance,

the inclination of said supporting surface relative to the fixed structure thereby being selectable by pivotal movement of said first and second linkage member means about said first, second, third and fourth position.

D. In a fourth aspect the invention consists in an infant warmer comprising:

base means,

support column means having a lower end mounted on said base means,

a partially enclosed article support structure as set out in paragraph A connected to said support column at a predetermined distance from said lower end, and

radiant heater means connected to said support column means, at a distance from said lower end greater than said predetermined distance, directed towards said partially enclosed article support structure.

BRIEF DESCRIPTION OF THE DRAWINGS

One preferred form of the present invention will now be described with reference to the accompanying drawings in which;

FIG. 1 is a front elevation of an infant warmer constructed in accordance with the present invention,

FIG. 2 is a side elevation of the infant warmer shown in FIG. 1,

FIG. 3 is a plan elevation of the infant warmer shown in FIG. 1,

FIG. 4 is an exploded up-side-down side elevation of one frame member from the mattress support structure of the infant warmer shown in FIG. 1,

FIG. 5 is an exploded plan view of the mattress support structure of the infant warmer shown in FIG. 1,

FIG. 6 is an enlarged view of a corner section of the mattress support structure shown in FIG. 5,

FIG. 7 is a side elevation of a part of the mattress support structure of the infant warm shown in FIG. 1 with a wall attached,

FIG. 8a is a front elevation of the infant warmer mattress support structure wall shown in FIG. 7,

FIG. 8b is a front elevation of a side extrusion into which the wall of FIG. 8a is inserted,

FIG. 8c is a plan elevation of the side extrusion shown in FIG. 8b,

FIG. 9 is a front elevation of a corner block cap assembly shown in FIG. 5,

FIG. 10 is a cross-sectional plan elevation through A--A of the corner block cap assembly shown in FIG. 9,

FIGS. 11a, 11b, 11c, 11d, 11e and 11f are side elevations of the infant warmer shown in FIG. 1 with the mattress support structure inclined at various different angles, and

FIG. 12 is an enlarged view of a section of the infant warmer shown in FIG. 11a showing the inclination adjustment linkage mechanism.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Infant Warmer Construction

With reference to the accompanying drawings and in particular FIGS. 1, 2 and 3, one preferred embodiment of an infant warmer open care bed 1 (referred to as "warmer" hereinafter) constructed in accordance with the present invention is shown. The infant warmer has a base portion 2 to which legs 3 are attached. Castors 4 are provided at the ends of the legs 3 to allow the warmer to be easily moved. A support column means, for example column 5 is mounted on base 2. In the preferred form, the column 5 comprises a "U" or "C" shaped aluminium extrusion with an open side 6.

The column 5 acts as a "back bone" to the warmer and serves two main functions, firstly to support a radiant heater head unit 7 at or near the upper end of the column and a partially enclosed article support structure or basinet 10 cantilevered near the center of the column, and secondly, for mounting a number of modular specific healthcare units, for example temperature control unit module 8 and resuscitation module 9 which are easily slotted into the open side 6 of the column extrusion and supplied with the necessary voltage, gases, etc. The basinet and its connection to column 5 will be further detailed below. The front panel of each module is provided with a cover plate having the required input and/or output sockets for connecting medical equipment such as breathing circuit conduits, and temperature sensors. The spaces in the extrusion which are not being utilized by a module may be covered by a face plate which may easily be removed to allow a further specific module to be retrofitted at a later date.

It can be seen from the drawings that the radiant heater head 7 has an open side 11 through which heat is directed towards a mattress 112 supported on basinet 10. In use, an infant is positioned on mattress 112 and warmed by the heat produced by the radiant heater head 7. The infant is readily accessible for medical treatment and the infant's temperature may easily be monitored (for example by a temperature sensor applied to the infant's skin) with the monitored temperature being fed back to a controller which may then moderate the power supplied to the heater element within the heater head unit 7. This temperature control system could be incorporated into a software program running on a microprocessor within one of the aforementioned modular units inserted into column 5.

Mattress Support (Basinet) Structure

The construction of basinet 10 will now be described in detail with reference to the drawings, in particular FIGS. 4 to 10.

It can be seen in FIG. 5 that the basinet has a frame, preferably comprising four (preferably equal length) rigid frame members, for example basinet extrusions 12, 13, 14 and 15 connected at their ends by corner blocks 16, 17, 18 and 19, supporting a flexible article support surface or mattress base or support 28. Each of the basinet extrusions are preferably light weight aluminium extrusions while the corner blocks are preferably plastic moldings or investment cast. The cross-section of each of the basinet extrusions is shown in FIG. 7.

FIG. 6 details the connection of two basinet extrusions (12 and 15) with a corner block (16). The corner block has two locating spigots 20 and 21 which fit within the basinet extrusions. In order to hold the corner block to both basinet extrusions, two bolts per extrusion (bolts 22 and 23 for basinet extrusion 15 and bolts 24 and 25 for basinet extrusion 12) are passed through holes in the corner block and into threaded holes, for example holes 26 and 27, within the each extrusion. This is repeated for each corner of the basinet.

A mattress support or base 28 which is preferably a substantially square sheet of material (preferably a light weight polyester with a PVC backing) in use supports a mattress, (preferably a closed cell foam mattress such as polyethylene) adapted to receive an infant. The mattress support material 28 is transparent to x-rays. A bead or piping 29 is formed around the sheet of material by sewing a thin plastics or rubber tube around the perimeter of the material although the corners may be excluded. The bead is inserted longitudinally within an open sided bead receiving slot 30 in the basinet extrusions allowing the mattress support material to be stretched across the frame. Due to the large diameter of the bead compared to the open side of the slot, the beading is not able to be pulled through the open side of the slot. The area of the mattress support material 28 is arranged to be slightly less than the area bordered by the frame to cause the assembled mattress support to be under tension thus providing a flat springy base for a mattress.

In order to assemble the basinet base, the bead around three edges of the mattress support fabric is inserted into the slots in three basinet extrusions which are then bolted together with two corner blocks to form a "U". The beading along the remaining side of material is then fed into the slot in the remaining extrusion and the remaining corner blocks are then bolted to this last extrusion. At this point, the extrusion which is added last may be rotated about its longitudinal axis in the direction of arrow 31 in FIG. 7 to position the corner blocks to allow the remaining bolts to be inserted. The rotation of the final extrusion tensions the mattress support material to ensure that a firm base is provided on which the mattress may then be positioned.

Mattress Retaining Side Walls

In order to protect an infant from drafts and to stop the infant from falling from the warmer, the basinet is preferably also provided with at least one removable article retaining wall means or side wall 32. In the preferred form four side walls are provided, so that the infant is enclosed on all sides by the warmer except for the side above the infant which is open to the ambient and through which heat is directed from the radiant heater unit 7. Preferably the side walls are manufactured from a tough rigid plastic or acrylic material. Notches, for example notches 37, are provided in the side wall for holding various tubes required for an infant's care.

With reference to FIG. 7, one side wall 32 is shown in its normal raised retaining position, however, the side walls of the basinet according to the preferred form of the present invention are able to fold down to a lowered, article (or infant) access position to allow unobstructed access to the infant. The side wall 32 is taped or crimped within a rectangular channel 33 of a further, preferably aluminium, side extrusion 34. A circular channel 35 is also provided along the length of side extrusion 34 into which a compression spring 36 is inserted. The circular slot may have an open side (as shown) which has a width small enough not to allow the compression spring to escape, alternatively the side wall could be provided with two short slots (one at either end) of, for example, 50 mm in length and two compression springs could be inserted (one in either short slot). The compression spring 36 (or both compression springs) is then compressed by inserting sliding axles 38 and 39 into either end of the circular slot and then the ends of the extrusion are crimped or a split pin or dowel pin is inserted to ensure that the sliding axles are unable to escape from the circular slot. The sliding axles are provided with thumb grips 40 to allow a user to move the sliding axle along the circular slot, facilitating the insertion or removal of the side wall to or from the basinet as will soon be described. The ends of the sliding axle are provided with a profiled stub which is substantially rectangular in cross-section, however the corners are rounded such that the cross-section of profiled stub 41 may be said to substantially form a "race track" shape.

In order to rotatably mount the side walls to the basinet, each of the corner blocks are provided with (preferably plastic) corner block caps 42, 43, 44 and 45 which are positioned over the corner blocks and are bolted to the corner blocks (for example bolt 46 fits into securing threaded hole 47 in corner block cap 42 as shown in FIG. 6).

With reference to FIGS. 9 and 10, each corner block cap is provided with two profiled holes 48 and 49 aligned in the same plane as the side and basinet extrusions. The profiled holes are substantially circular in cross-section with a segment of the circle removed to leave a substantially "horse shoe" cross-sectionally shaped profiled hole. A compressible cylindrical tube 50 is forced into each profiled hole. The compressible tube may be, for example, manufactured from urethane or any other suitable compressible substance. Upon insertion into the profiled hole the cylindrical tube 50 deforms to the substantially "horse shoe" shape of the hole.

A dummy axle 51, having a tubular portion 52 and a stub axle receiving portion, or profiled locating hole 53, has its tubular portion 52 inserted into the compressed tube 50. The tubular portion has a cross-sectional shape which is substantially elliptical so that the dummy axle will need to be aligned correctly with the profiled hole 53 to allow insertion. Once inserted rotation of the dummy axle will be possible within tube 50 although the ease of rotation will vary depending on the rotational alignment of the tubular portion within the profiled hole. As the widest cross-section of the dummy axle 51 is rotated into alignment with the narrow part of the profiled hole, the friction between the dummy axle 51 and the cylindrical tube 50 will increase. The stub axle receiving portion 53 of dummy axle 51 has an opening which is designed to be a locking fit with the profiled stub of the sliding axles.

Accordingly, in order to assemble the side walls to the basinet, firstly the corner block caps (with their urethane tubes and dummy axles inserted) are bolted to each of the corner blocks. Each of the assembled side walls (with the walls inserted into their extrusions and the axles inserted within their slots) are then in turn positioned adjacent a frame extrusion. The installer must then force the two sliding axles within the side wall extrusion towards the center of the wall so that the stub axles are withdrawn inside the circular slot. The side wall is then moved into position between two corner block caps with the sliding axles of the wall aligned with the dummy axles of the corner blocks. The installer then allows the sliding axles to spring outwards so that the profiled stubs align with and lock into the profiled openings in the dummy axles. The side wall is then installed. Removal of the side wall is carried out by sliding the sliding axles inwards towards the center of the side wall and simply removing the wall.

In order to lock the side wall at its normal operating position, that is its raised position as shown in FIGS. 1, 2 and 7, the wall extrusion is provided with a latching hook 54 which extends out from the side of the extrusion adjacent the warmer. A plastic clip extrusion 55 (preferably a plastics or rubber extrusion or more preferably a plastic molding) is inserted into a specially designed slot in each basinet extrusion. The plastic clip extrusion 55 allows the latching hook 54 to be inserted with minimal force but requires a larger force to remove the latching hook. Thus the side walls are easily locked into their raised retaining position and will not accidentally be knocked from this position, requiring intentional unclipping by an operator of the warmer. The previously described construction of axle for the side walls allows the sides to be lowered quietly without the user needing to physically guide the walls the entire 180° down. Once unclipped, the user may let go of the side wall and rely on the frictional axle connection to damp the fall of the wall. The wall will eventually reach its lowered access position with no sudden noise or movement which would otherwise startle the infant.

In an alternative preferred embodiment, the interlocking system of the above described dummy axle 51 and sliding axle 38, 39 may be transferred so that the dummy axle 51 is provided with a profiled stub (rather than a profiled hole) and the sliding axles 38, 39 are provided with profiled holes (rather than profiled stubs).

Basinet Support Mechanism (Non-Parallel Links)

With reference now particularly to FIGS. 1, 2, 11a to 11f and 12, the above described basinet with removable fold-down sides is attached to the support column 5 by an inclination adjusting linkage arrangement. The linkage arrangement comprises two link members 60 and 61. Preferably each link member is "U" shaped and the two legs of the link member are pivotally attached to either side of the support column 5 at their proximal ends. Preferably, but not necessarily, the link members are the same length. It can be seen in FIG. 12 that link member 61 is connected to the column 5 through pivot point 62 while pivot member 60 is connected to column 5 through pivot point 63.

Preferably a channel 64 is provided in each side of the column and "T" shaped sliding blocks are positioned within the channel so that they may slide up and down the channel but may not be withdrawn therefrom. Preferably the pivot points 62 and 63 are connected into the aforementioned "T" shaped sliding blocks to allow rapid height adjustment of the basinet relative to the support column 5. Upon tightening the screw or bolt connecting the linkage member to its "T" shaped sliding block, the "T" shaped block is firmly frictionally held in position in the channel although still allowing free rotational movement of the linkage members about their connection to the column 5. Upon tightening, it will be observed that a fixed distance (a first predetermined distance) has been set between the two pivot points 62 and 63.

The distal ends of the link members are attached to two mounting brackets 65 and 66 which are connected (preferably screwed) at their upper ends within a specially shaped channel in the basinet extrusion closest to the column 5. The distal ends of the link members 60 and 61 are pivotally connected to the mounting brackets at pivot points 67 and 71 respectively. It can be seen that there is a fixed distance (a second predetermined distance) between pivot points 67 and 71. By ensuring that the first predetermined distance is preferably less than the second predetermined distance, it is possible to adjust the angle of inclination of the basinet with respect to the column 5 to adapt the angle of the infant in relation to medical personnel or medical equipment as the situation dictates (such as to allow surfactant administration to an infant). Thus the juxtaposition of the link members which are constrained to rotate about their proximal pivot points on the column with the added constraint that the distance between their distal ends is fixed, produces a non-parallel linkage arrangement which allows the basinet to be tilted without the need for a large supporting or tilting structure to be positioned directly below the basinet. The area directly below the basinet is thus free to be used for storage or, for example, to allow modern portable x-ray equipment to be positioned directly beneath the infant.

It has been found that the above described linkage arrangement produces an instantaneous link center 68 about which the basinet pivots. The instantaneous link center changes position slightly depending on the basinet angle thus creating a "virtual pivot centre" 69 which comprises the locus of all possible instantaneous link center positions. It has been found that the virtual pivot centre is substantially elliptical in shape. By adjusting the position of the virtual pivot centre (for example by altering the length or positioning of link members 60 and 61), the basinet may be made to pivot about the center of the mattress (as shown in FIG. 12) which is the optimal position for pivoting an infant supported by the mattress.

A braking mechanism is included in order to lock the basinet into position once a selected angle of inclination has been established. The braking mechanism preferably acts to lock the two link members in position relative to each other. An example of a suitable braking mechanism is a multi-plate brake 70, similar to those utilized in modern office chairs to adjust and lock the seat back angle, basically utilizing a friction force to oppose movement. A handle (not shown) may be hidden beneath one of the basinet extrusions with a cable connected to release the multi-plate brake and allow the basinet to be tilted to a new angle at which time the handle may be released and the basinet tilt angle will again be locked. Alternatively a hydraulic piston could be used to provide an opposing force.

Thus, at least in the preferred form, the present invention provides an economical, low cost, low weight and easily assembled infant warmer. The basinet construction allows modern medical equipment to be positioned very near to the infant and yet provides a stable and nurturing environment for a new born baby to receive treatment. The linkage arrangement enables the space beneath the warmer to be more beneficially utilized and also reduces changes in distance between the infant and the radiant heat source, enabling temperature regulation of the infant to be more easily maintained. 

We claim:
 1. An article support structure for supporting an infant, comprising:a support surface; a fixed structure; and an inclination adjusting linkage arrangement to connect said support surface to said fixed structure, said inclination adjusting linkage arrangement including first linkage member having proximal and distal ends, pivotally connected to said fixed structure at said proximal end at a first position on said fixed structure, second linkage member having proximal and distal ends, pivotally connected to said fixed structure at said proximal end at a second position on said fixed structure, there being a first predetermined distance between said first and second positions, wherein the distal ends of said first and said second linkage members are each pivotally connected to said support surface at third and fourth positions respectively, there being a second predetermined distance between said third and fourth positions which is not equal to said first predetermined distance, the inclination of said support surface relative to the fixed structure thereby being selectable by pivotal movement of said first and second linkage members about said first, second, third and fourth positions, and said support surface pivots about an imaginary pivot axis due to said inclination adjusting linkage arrangement and the adjustment of the inclination of said support surface causes said imaginary pivot axis to trace out a pivot region.
 2. An article support structure as claimed in claim 1 wherein said second predetermined distance is less than said first predetermined distance.
 3. An article support structure as claimed in claim 1 wherein said first and said second linkage members are "U" shaped, each having substantially parallel leg portions connected by a cross member, wherein the cross members are positioned at the distal end of the linkage members.
 4. An article support structure as claimed in claim 3 wherein said support structure comprises at least one column having two substantially parallel sides wherein the respective parallel leg portions of each linkage member are connected to respective sides of said at least one column.
 5. An article support structure for supporting an infant, comprising:a support surface; a fixed structure; and an inclination adjusting linkage arrangement to connect said support surface to said fixed structure, said inclination adjusting linkage arrangement including first linkage member having proximal and distal ends, pivotally connected to said fixed structure at said proximal end at a first position on said fixed structure, second linkage member having proximal and distal ends, pivotally connected to said fixed structure at said proximal end at a second position on said fixed structure, there being a first predetermined distance between said first and second positions, wherein the distal ends of said first and said second linkage members are each pivotally connected to said support surface at third and fourth positions respectively, there being a second predetermined distance between said third and fourth positions which is not equal to said first predetermined distance, the inclination of said support surface relative to the fixed structure thereby being selectable by pivotal movement of said first and second linkage members about said first, second, third and fourth positions, and wherein said support surface includes a flexible article support surface, rigid frame means for supporting said flexible article support surface, and mounting bracket means for attachment between said frame means and the distal ends of said first and second linkage members.
 6. An article support structure for supporting an infant, comprising:a support surface; a fixed structure; and an inclination adjusting linkage arrangement to connect said support surface to said fixed structure, said inclination adjusting linkage arrangement including first linkage member having proximal and distal ends, pivotally connected to said fixed structure at said proximal end at a first position on said fixed structure, second linkage member having proximal and distal ends, pivotally connected to said fixed structure at said proximal end at a second position on said fixed structure, there being a first predetermined distance between said first and second positions, wherein the distal ends of said first and said second linkage members are each pivotally connected to said support surface at third and fourth positions respectively, there being a second predetermined distance between said third and fourth positions which is not equal to said first predetermined distance, the inclination of said support surface relative to the fixed structure thereby being selectable by pivotal movement of said first and second linkage members about said first, second, third and fourth positions; and braking means attached between said first and said second linkage members for allowing the selected inclination of said support surface to be substantially locked once selected.
 7. An article support structure having an inclination comprising:a support surface; a fixed structure; and an inclination adjusting linkage arrangement to connect said support surface to said fixed structure, said inclination adjusting linkage arrangement including a first linkage member having proximal and distal ends, pivotally connected to said fixed structure at said proximal end at a first position on said fixed structure, a second linkage member having proximal and distal ends, pivotally connected to said fixed structure at said proximal end at a second position on said fixed structure, there being a first predetermined distance between said first and second positions, wherein the distal ends of said first and said second linkage members are each pivotally connected to said support surface at third and fourth positions respectively, there being a second predetermined distance between said third and fourth positions which is not equal to said first predetermined distance, the inclination of said support surface relative to the fixed structure thereby being selectable by pivotal movement of said first and second linkage members about said first, second, third and fourth positions, and said support surface pivots about an imaginary pivot axis due to said inclination adjusting linkage arrangement and the adjustment of the inclination of said support surface causes said imaginary pivot axis to trace out a pivot region which is elliptical in shape. 